Study on Fracture-Split Performance of 36MnVS4 and Analysis of Fracture-Split Easily-Induced Defects

The material 36MnVS4 is the second generation of connecting rod fracture-split material. However, it generates more quality defects during the fracture-split process. To investigate the causes of defects that occurred, the material properties and fracture-split performance of the 36MnVS4 are researched and compared with C70S6. The fracture-split easily-induced defects are also analyzed. By finite element simulation and experimental analysis, the results show that the 36MnVS4 has lower carbon content and more ferrite, therefore the fracture surface of the 36MnVS4 connecting rod is more prone to tears and the plastic deformation range is greater. The fracture speed of the 36MnVS4 connecting rod is 20% lower than that of the C70S6 connecting rod. The slower fracture separation rate increases the possibility of defects generation. The crack initiation position of the 36MnVS4 connecting rod is random, scattered, and unstable, and the 36MnVS4 has higher gap sensitivity. Therefore, the 36MnVS4 connecting rod is more prone to produce quality defects in the fracture-split process. By changing the cross-section design, the outer edge of the joint surface is changed to arc-shaped, which can improve the fracture-split process of the 36MnVS4 connecting rod and reduce the processing defects.